package com.liang.listener;

import javax.servlet.ServletContext;
import javax.servlet.http.HttpSession;
import javax.servlet.http.HttpSessionEvent;
import javax.servlet.http.HttpSessionListener;

//统计网站在线人数：统计session
public class OnlineCountListener implements HttpSessionListener{

    //创建Session监听：看你的一举一动
    //一旦创建session就会触发一次这个事件！
    @Override
    public void sessionCreated(HttpSessionEvent se) {
        ServletContext ctx = se.getSession().getServletContext();
        Integer onlineCount = (Integer) ctx.getAttribute("OnlineCount");

        if(onlineCount==null){
            onlineCount = new Integer(1);
        }else{
            int count = onlineCount.intValue();
            onlineCount = new Integer((count+1));
        }

        ctx.setAttribute("OnlineCount",onlineCount);
    }

    //销毁Session监听
    //一旦销毁session就会触发一次这个事件！
    @Override
    public void sessionDestroyed(HttpSessionEvent se) {

    }
}
